Ovarian cancer is a serious threat and ranks among the top leading causes of cancer deaths among women in the United States. It affects 1 in 58 women living in the U.S. It is estimated that 20,180 women will be diagnosed with ovarian cancer in 2006 and approximately 15,310 women will die of the disease (www.ovariancancer.org). Survival rates are low when the diagnosis is in the advanced stages. Ninety five percent of women diagnosed with advanced stage disease will survive no longer than 5 years. The standard of treatment for patients with advanced-stage ovarian cancer in the last decade has been surgery followed by platinum-based chemotherapy. Although 80% of the patients who are treated with this regimen initially show improvement, the cancer recurs in a majority of them. Patients with advanced ovarian cancer who do not respond to initial therapy or those with recurrent disease are severely limited in therapeutic options. Identification of safer and more effective treatments is a critical need for these patients. For example, one potential improvement in treatment might be the delivery of therapeutic agents directly to the abdominal cavity since it directs treatment to the site of the tumor. Gene transfer into genomes of human cells has been shown using the Sherping Beauty transposon system derived from teleost fish sequence as taught, for example, in Geurts et al., Molecular Therapy, Vol. 8, No. 1, July 2003, pp. 108-117, which is incorporated herein in its entirety, by reference. Ivics et al., Cell, Vol. 91, Nov. 14, 1997, pp. 501-510, teaches the amino acid sequence of SB10, SEQ. ID. NO. 1, for example; which is incorporated herein in its entirety by reference. The sequence listings in the references incorporated by reference herein are now and are likewise incorporated herein.
The lack of specific symptoms, the relative inaccessibility of the ovaries deep in the pelvis, and the absence of specific marker(s) represent barriers for early detection (Bast R C et al Cancer Treat Res. 2002; 107:61-97; Pepe M S, et al. J Natl Cancer Inst. 2001; 93:1054-1061). In most cases, ovarian cancer is diagnosed at a late stage (Goodman M T et al. Cancer. 2003; 97(Suppl 10): 2648-2659). Furthermore, our understanding of the early pathogenesis of ovarian cancer has been hindered by the lack of sufficient number of patients with early-stage disease (Goodman M T et al. Cancer. 2003; 97(Suppl 10): 2648-2659; Reis L A Cancer. 1993; 71(Suppl 2):524-529; Holschneider C H, Berek J S. Semin Surg Oncol. 2000; 19:3-10). Animal models of human diseases are widely used to address questions of tumor development. Selection of a particular animal model depends upon a variety of factors, among them: animal cost, species lifespan, and hardiness; availability of biomolecular and genetic tools for that species; and evolutionary distance from humans. Animal models are used to elucidate disease etiologies and pathogenesis that are difficult to study in humans. Although large domestic mammals including bovine have similar reproductive traits and develop ovarian cancer spontaneously similar to humans, the low incidence rate, multiple pregnancies, longer gestation, and lactation period make them an inappropriate model for human ovarian cancer. On the other hand, a number of rodent models, induced or genetically manipulated, have been developed and used successfully to elucidate some aspects of ovarian cancer. Chickens (Gallus domesticus) also develop spontaneous ovarian cancer with a high incidence rate (Damjanov I. Curr Top Pathol. 1989; 78:1-10; Fredrickson T N. Environ Health Perspect. 1987; 73:35-51). However, the nonspontaneous nature (Stakleff K D, Von Gruenigen V E. Int J Gynecol Cancer. 2003; 13:405-412; Vanderhyden B C, et al Reprod Biol Endocrinol. 2003; 1:67) and the time taken to develop cancers of some of these models and lack of resemblance to human disease limits their clinical relevance. In this study, we have developed a robust method to develop cancers rapidly in non-human primates, which closely resemble to humans and will permit screening of cancer drugs for safety and efficacy.
Ovarian cancer, like all cancers, is associated with genetic mutations and, therefore, gene therapy offers a promising approach for its treatment. However, gene therapy is limited by unacceptable risks from the use of viral vectors and by the lack of a system for targeting anticancer drugs to specific cancer cells. We proposed a gene therapy strategy combining nanotechnology and the Sleeping Beauty transposon-based nonviral gene transfer system (Ivics Z, et al Cell 1997, 91(4):501-510; Geurts A M et al; Mol Ther 2003, 8(1):108-117; Cui Z, et al J Mol Biol 2002, 318(5):1221-1235) to achieve targeted delivery of DNA-based drugs to cancer cells for treatment of ovarian cancer. See also, U.S. Pat. No. 6,489,458 which is incorporated herein in its entirety. Over the past few years, we have developed modified chitosan particles as platforms for DNA-based therapy. Chitosan, a natural biocompatible cationic polysaccharide extracted from crustacean shells, has good potential for the delivery of genes and drugs, as it combines the ability to protect DNA from nucleases and slow-sustained release of DNA [M Kumar, et al Hum Gene Ther 2002, 13:1415-25.1], which is herein incorporated by reference in its entirety.
We have identified a novel natriuretic peptide, NP73-102, as a candidate drug for cancer. First, we investigated if stable expression of NP73-102 mediated by the Sleeping Beauty nanotransposon (SB) [15-17] could protect mice from developing ovarian cancer. We also tested another N-terminal natriuretic peptide, vessel dilator (VD) for anticancer properties in the nude mouse model. Our study showed that both VD and NP73-102 provided protection against ovarian cancer in mouse models. Secondly, we investigated if VD and NP73-102 provided protection against ovarian cancer in nonhuman primate models. We used novel nanoparticles containing siRNAs for p53 and pRb and mutant K-Ras to induce ovarian tumors in rhesus monkeys and then treat the animals with pSB11-NP73-102/VD nanoparticles. Our nonhuman primate model studies confirmed that Sleeping Beauty-mediated nanotransposon expressing natriuretic peptides protect against ovarian cancer development.
Currently, most of the anti-cancer drug evaluations were carried out by using murine models, such as SKOV3/nude mouse model or ID8/C57BL/6 model. However, humans differ from mice. The Applicant has proposed to evaluate TGN208 in non-human primates, using a Rhesus monkey model, for example. This model is an excellent ovarian cancer model for chemoprevention studies, because Rhesus monkeys have similar ovarian and menstrual systems as humans. It is thought, without being limiting in any way, that results from such primate models will be more relevant in guiding research and development of therapies in humans than less similar models such as mice and chicken.